Catch the falling stars
A CHINESE New Year fireworks display in the heat of the summer? Not quite, but the skies will be ablaze on Thursday when a meteor shower hits Hong Kong.
Through to August 18, Perseids - a meteor shower originating from comet Swift Turtle - will be visible in the northeastern sky after midnight.
The shower is expected to be the biggest to hit the territory and up to 600 meteors per hour are expected to crash through the Earth's atmosphere at its peak.
But experts say the meteors are unlikely to be big enough to hit the Earth as more than 90 per cent usually burn out well before they reach the ground.
Often called ''shooting'' or ''falling stars'', meteors are streaks of light which result from an entry of an inter-planetary particle into the Earth's atmosphere at high speed.
''Meteor showers are debris and filaments from the comet and there are fixed times when they appear,'' said the Space Museum's assistant curator Wong Yiu-wah.
He said meteor showers could be sighted when the Earth's orbit intersected with the orbit of a comet.
Meteors emanate from a particular point on the celestial sphere known as a radiant. About 10 major showers occur each year - Perseids being one of them - with rates of 10 to 100 meteors per hour. Nearly all showers are named after the constellation in which the radiant lies.
There are two types of meteor showers: periodic or permanent. The meteorites of a permanent shower are evenly distributed around their orbit and may produce visual meteors every year at the same time.
However in the periodic, younger showers such as Perseids, the meteorites are close together and may produce, over a period of several years, very spectacular showers of falling stars.
Perseids has been spotted around the same time in August for the past 100 years but from 1991 there has been an increase from around 80 meteors per hour to more than 150.
While it is hard to predict, Mr Wong said at the peak between 2 am and 3 am on August 12, we could see a storm of 400 to 600 meteors per hour.
Over the next week, the viewing time will decrease and the number of meteors per hour could drop to around 10.
Mr Wong said a typical meteor trail occurred at a height of at least 60 kilometres above the Earth's surface. There should be no difficulty in spottingthe meteor shower - expensive equipment should not be necessary.
Mr Wong said the shower could be spotted from anywhere in the territory but areas with less pollution would give a better vantage point as only bright meteors would show up in urban areas.
Photographers should use a 400 ASA film on a long-time exposure of about five minutes, and a wide angle lens would increase the chances of capturing the meteors on film.
